Jean-Marie Le Pen, a far-right nationalist, is in fourth place in the polls and appears to be the only one of the other 12 candidates with a chance of qualifying for the run-off on May 6.
Many French voters are undecided on who to support in the election. A poll published Sunday by the CSA-Cisco agency suggested that 42 per cent of French respondents have not yet made their choice.
Many people in France no longer feel allegiance to political parties, traditionally a strong factor in French politics.
"I am a woman, a mother of four children, I have my feet on the ground, I am practical, I am a free woman"
Segolene Royal in her television campaign spot
France's presidential hopefuls
There is a feeling of uncertainty of which candidate would best replace Jacques Chirac, France's current president.
France's broadcast regulator has allotted each candidate 45 minutes of campaign airtime on public TV and radio channels until April 20, two days before the first round.
Royal took a simple approach in her first broadcast, addressing voters against a backdrop of blue sky.
"I am a woman, a mother of four children, I have my feet on the ground, I am practical, I am a free woman," she said.
Sarkozy in his campaign broadcast focused on the main themes of his campaign: employment and immigration.
"Action is my life's passion," said Sarkozy, who pledged to abandon past policies to resolve high unemployment and improve the integration of immigrants.
Bayrou, the centre candidate, said he was uniquely placed to unite the French people.
"I want to be the president who brings the French together. It's the only way to rebuild France," he said.
Le Pen took a more adversarial approach to his campaign broadcast.
He accused front-runners Sarkozy and Royal of latching onto his campaign themes of immigration and national identity, telling voters to choose the "original over the copy."
Of the 12 candidates, seven of them have less than 5 per cent of support according to polls.
Liberation newspaper complained that France's campaign system of perfect equality in airtime was "absurd," saying it would only confuse undecided voters.